Inspection Procedure 2

INSPECTION PROCEDURE 2: When the Ignition switch is turned "ON" (engine stopped or after start-up), the TCL warning light does not illuminate.








CIRCUIT OPERATION
- Power to the TCL warning light is supplied from the ignition switch. The ABS-ECU grounds the circuit to illuminate the light.
- The ABS-ECU illuminates the TCL warning light for 3 seconds while running self-check. This light can be illuminated for 3 seconds upon start-up or ignition switch ON, engine stopped.

TECHNICAL DESCRIPTION (COMMENT)
The cause may be: an open circuit in the TCL warning light power supply circuit, a blown TCL warning light bulb or ABS-ECU.

TROUBLESHOOTING HINTS
- Blown fuse
- Damaged wiring harness or connector
- Burnt out TCL warning light bulb
- Malfunction of the ABS-ECU

DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set





STEP 1. Check the power supply circuit at ABS-ECU connector A-02.
1. Disconnect connector A-02 and measure at the harness side.
2. Ground the terminal 20.
3. Turn the ignition switch to the "ON" position.
Q: Does the TCL warning light illuminate?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 9.
NO: Go to Step 2.

STEP 2. Check the TCL indicator light bulb.
1. Remove the combination meter.
2. Check the TCL indicator light bulb.
Q: Is the TCL indicator light bulb burned out?
YES: Replace the bulb and then go to Step 9.
NO: Go to Step 3.





STEP 3. Check the combination meter for the continuity.
1. Remove the combination meter.
2. Remove the TCL indicator light bulb. Then measure the resistance between the bulb terminals.
3. Install the TCL indicator light bulb to the combination meter, and then measure the resistance between connector C-101 terminals 52 and 42. The resistance reading at this time should be much the same as the resistance measured at step (2).
Q: Are the two resistance values extremely different each other?
YES: Replace the combination meter (printed circuit board).
NO (much the same): Go to Step 4.





STEP 4. Check the power supply circuit at the combination meter.
1. Disconnect connector C-101, and check at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 52 and ground. It should be approximately 12V (battery positive voltage.).
Q: Is the voltage approximately 12 V?
YES: Go to Step 5.
NO: Go to Step 7.











STEP 5. Check connectors C-101, C-212, and A-02. Check connectors C-101, C-212, and A-02.
Q: Are any of connectors damaged?
YES: Repair it and then go to Step 9.
NO: Go to Step 6.








STEP 6. Check the continuity between the combination meter and the ABS-ECU. Check the continuity between combination meter connector C101 and ABS-ECU connector A-02.
Q: Is there the continuity between combination meter connector C-101 and ABS-ECU connector A-02?
YES: Go to Step 9.
NO: Repair the harness wire and then go to Step 9.








STEP 7. Check connectors C-101, C-308, and C-301. Check connectors C-101, C-308, and C-301.
Q: Are any of the connectors damaged?
YES: Repair it and then go to Step 9.
NO: Go to Step 8.





STEP 8. Check the continuity between the Ignition switch (IG1) and the combination meter.
Q: Is there any continuity (less than 2 ohm) between the Ignition switch (IG1) and combination meter connector C-101 ?
YES: Go to Step 9.
NO: Repair the harness wire and then go to Step 9.

STEP 9. Check symptoms
Q: Does the TCL warning light Illuminate for 3 seconds when the ignition switch is turned to the "ON" position with engine stopped or upon start-up?
YES: This diagnosis is complete.
NO: Return to Step 1.